The present invention relates to an industrial control systems using connected messaging for highly reliable time critical control, and, in particular, to methods, systems and apparatuses allowing dynamic formation of connections between advanced process control (“APC”) components and existing industrial controllers when advanced process control components are added or need to accommodate hardware changes.
Industrial controllers are special purpose computers used for controlling factory automation and the like. Under the direction of stored programs, a processor of the industrial controller examines a series of inputs reflecting the status of a controlled process and changes outputs affecting control of the controlled process. The stored control programs may be continuously executed in a series of execution cycles, executed periodically, or executed based on events.
The inputs received by the industrial controller from the controlled process and the outputs transmitted by the industrial controller to the controlled process are normally passed through one or more input/output (I/O) modules which serve as an electrical interface between the controller and the controlled process. The inputs and outputs are recorded in an I/O data table in processor memory as control level data. Input values may be asynchronously read from the controlled process by specialized circuitry. Output values are written directly to the I/O data table by the processor, and then communicated to the controlled process by the specialized communications circuitry.
In contrast to more conventional computer systems, industrial control systems generally provide for a more rugged construction resistant to environmental contamination. In addition industrial control systems normally provide a modular architecture providing greater flexibility and hardware configuration (to match a variety of different control applications), often including distributed processing of multiple programs. In this regard, an industrial control system may be assembled among multiple programmable controllers connected to an arbitrary number of I/O modules (generally hardened and fault tolerant hardware) augmented with advanced process control components which may be distributed within programmable controllers or within supervisory computer systems having a higher level of computational power but not necessarily hardened or fault tolerant.
The various components of the industrial control system may be connected together by means of a high-speed “control network” using a variety of special protocols that ensure predictable, timely and reliable communication of control data. Typically, control network protocols will employ “connected messaging” in which the bandwidth of the network and buffer space is pre-allocated to dedicated “connections” to specific hardware elements to prevent lost, unpredictably delayed data transfer, or misdirected data transfer that can occur in standard network protocols such as Ethernet alone. Examples of connected messaging include Common Industrial Protocol (“CIP”) connected messaging, including as described in “The Common Industrial Protocol (CIP™) and the Family of CIP Networks,” Publication Number PUB00123R0, Copyright 2006, which is hereby incorporated by reference in its entirety.
The demands of connected messaging can create significant bathers to rapid commissioning of an industrial control system because specific route information is necessary to establish a connection (typically including an identification of the hosting hardware associated with the software component) and this route information is not fully available until the last stages of commission. Accordingly, partial operation or testing of the industrial control system is delayed. Connected messaging therefore presents particular problems with advanced process control which normally requires access to control level data in multiple different controllers and when hardware changes are made in the underlying control network requiring multiple changes in underlying connection data.